HP 100BaseT User's Guide download pdf (Page 15)

HP Hub-8TXE Installation and Reference Guide

Installing the System 2-3

Making a Connection via the MDI Cascade Port

1. To make a direct connection to another compatible repeater or switch, use the

8MDI cascade port. When connecting to this port, remember not to use port

8MDI-X.

2. Prepare straight-through shielded or unshielded twisted-pair cables with RJ-45

plugs at both ends. Use 100

W Category 5 cable for all connections. Connect

one end of the cable to Port 8MDI on this hub, and the other end to a standard

MDI-X port on the other device. When inserting an RJ-45 plug, be sure the

tab on the plug clicks into position to ensure that it is properly seated.

Notes:

1. When connecting to Port 8MDI, do not use Port 8MDI-X.

2. Make sure the length of twisted-pair cable does not exceed 100 meters.

3. To connect to another hub or switch, you may also run straight-through

twisted-pair cabling from an MDI-X port on this hub to a cascade port on

another device. However, if you must connect to another hub or switch via

similar port types at both ends of the cable, use crossover cabling.

Distance Limit for Fast Ethernet Cabling

For 100Base-TX, network diamter is very important, because each packet must

propagate through the Ethernet collision domain before the next packet is sent.

Every 100Base-TX hub (repeater) adds a small propagation delay to the packet,

which can be equated to a certain number of bit times. The propagation delay

(repeater delay) of the HP Hub-8TXE is 80 bit times, or a cable equivalent

length of 72 meters.

The 100Base-TX maximum cable distance (“network diameter”) is 367 meters.

And the maximum distance from a hub to an end-node is 100 meters. To

cascade two 100Base-TX Hub-8TXEs together, we must do this calculation:

For an end-node on one hub to communicate with an end-node on the other

hub, the cable distance from end-nodes to hubs would be 100m + 100m

(perhaps a bit less, but we should consider “worst case”). The packets would

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HP 100BaseT User's Guide Page 15